SummaryOrganic sulfur is stored as glutathione (GSH) in plants. InArabidopsis, γ-glutamyl cyclotransferases (GGCT2;1, GGCT2;2, and GGCT2;3) degrade cytosolic GSH, but they do not fully explain the rapid GSH turnover. Here, we demonstrate that γ-glutamyl peptidases, GGP1 and GGP3, play a substantial role in degrading GSH in the cytosol.We conducted yeast complementation assay and activity assay of recombinant proteins to identify the novel GSH degradation enzymes. The expression patterns were investigated by RT-qPCR. GSH concentrations in the mutants were also analyzed.GGP1complemented the yeast phenotype. Recombinant GGP1 and GGP3 showed reasonableKmvalues considering cytosolic GSH concentration, and their activity was comparable to that of GGCTs. TheGGP1transcript was highly abundant in mature organs such as rosette leaves. The expression ofGGCT2;1was conspicuously enhanced under sulfur deficiency. GSH concentration was higher inggp1knockout mutants regardless of nutritional conditions; the concentration was higher inggct2;1knockout mutants under sulfur-deficient conditions.We propose a model wherein cytosolic GSH is degraded fundamentally by GGP1. The degradation is accelerated by GGCT2;1 under sulfur deficiency. Given the energy cost throughout the reactions, GGPs could render a more efficient route for GSH degradation than GGCTs.